diff --git a/scripts/check_pr_perimeter.py b/scripts/check_pr_perimeter.py
index ccfa04f6e8..1f3a29f117 100644
--- a/scripts/check_pr_perimeter.py
+++ b/scripts/check_pr_perimeter.py
@@ -1572,7 +1572,24 @@ def _extract_line_candidates(text: str) -> list[tuple[int, str]]:
                 continue
             candidates.append((idx, line))
             continue
-        if _has_exclusivity(low) and any(w in low for w in STRONG_SCOPE_WORDS):
+        # #15833/#15846: the scope-word test goes through `_has_strong_scope`,
+        # NOT a plain substring scan. The whole-word guard already exists and is
+        # already used by the two other call sites (l.~1168, l.~1257); this one
+        # was never migrated, so it kept matching scope words INSIDE longer
+        # words. Two measured misfires, both on a line whose subject is not the
+        # PR perimeter at all:
+        #   #15833 l.45 "`--dist loadscope`, jamais `load` [...] il est sur
+        #     **uniquement** grace a ce groupement" -- 'scope' inside
+        #     "loadscope". #12718 added the `(?<![-\w])scope(?![-\w])`
+        #     lookbehind to `_has_strong_scope` for exactly this shape.
+        #   #15846 l.44 "cette ligne ne peut pas **changer** le comportement de
+        #     build" (marker "seulement" earlier on the line) -- 'change'
+        #     inside "changer". #11800 added the `\b` boundary to
+        #     `_has_strong_scope` for exactly this shape ("inchanges").
+        # Both guards were built, tested, and then bypassed here. Same failure
+        # family as the "read-only" (#11654) and "pas seulement" (#12547)
+        # misfires above: the marker is present, its force is not.
+        if _has_exclusivity(low) and _has_strong_scope(low):
             if _markers_all_quoted(line):
                 continue  # quoting an exclusivity claim, not making one
             candidates.append((idx, line))
diff --git a/scripts/tests/test_check_pr_perimeter.py b/scripts/tests/test_check_pr_perimeter.py
index c7dbe9793f..9f6aefad04 100644
--- a/scripts/tests/test_check_pr_perimeter.py
+++ b/scripts/tests/test_check_pr_perimeter.py
@@ -230,6 +230,57 @@ def test_extract_skips_read_only_compound():
         "permissions read-only inchangées")
 
 
+def test_extract_skips_scope_word_inside_a_longer_word():
+    r"""A strong scope word must be a WHOLE word -- at the extraction site too.
+
+    `_has_strong_scope` has carried that guard for a while: #11800 added the
+    `\b` boundary so "inchanges" stops supplying 'change', and #12718 added
+    the `(?<![-\w])scope(?![-\w])` lookbehind so "out-of-scope" stops
+    supplying 'scope'. Two of its three call sites went through it;
+    `_extract_line_candidates` kept a plain substring scan, so the guard was
+    built, tested, and then bypassed on the path that feeds the report.
+
+    Both lines below are measured, taken verbatim from PRs whose real
+    perimeter is a single file and whose bodies assert nothing false about
+    it -- the misfire turned the required `Always-on guards` red on two lanes
+    at once:
+
+    * #15833 l.45 -- 'scope' inside "loadscope", marker "uniquement".
+    * #15846 l.44 -- 'change' inside "changer", marker "seulement".
+
+    Same failure family as the "read-only" compound above (#11654) and "pas
+    seulement" (#12547): the marker is present, its force is not.
+    """
+    loadscope = (
+        "1. **`--dist loadscope`, jamais `load`.** `loadscope` groupe par "
+        "module, donc les tests d'un module ne tournent jamais concurremment "
+        "entre eux : il est sur **uniquement** grace a ce groupement."
+    )
+    changer = (
+        "Le workflow de `main` est `c631a7a9` : `schedule` + `dispatch` "
+        "seulement, aucune jambe PR. Cette ligne ne peut pas changer le "
+        "comportement de build."
+    )
+    assert extract_perimeter_assertions(loadscope) == []
+    assert extract_perimeter_assertions(changer) == []
+    assert not _has_strong_scope(loadscope.lower())
+    assert not _has_strong_scope(changer.lower())
+
+
+def test_whole_word_scope_still_extracts_real_declarations():
+    """Positive control for the guard above: it must not silence the real
+    thing. Each line carries a STANDALONE scope word and stays a perimeter
+    assertion -- first among them the founding #11227 sentence, which is what
+    this organ exists to catch."""
+    for line in (
+        "**Perimetre** : 2 fichiers twins uniquement, aucune autre modification.",
+        "Cette PR touche uniquement ces fichiers, aucune autre modification.",
+        "Scope: only the workflow file, nothing else.",
+        "lake 70 fichiers uniquement, scope = perimetre PR",
+    ):
+        assert extract_perimeter_assertions(line), line
+
+
 def test_only_standalone_still_flags():
     """The control positive side: a standalone "only" with a scope word stays
     a live exclusivity assertion -- the fix must not kill the English arm."""